1. Field of the Invention
The present invention relates to a microwave and millimeter wave circuit apparatus used as a high-frequency module for a communication apparatus, radar, or the like and in more particular, to a microwave and millimeter wave circuit apparatus capable of reducing a transmission loss.
2. Description of the Related Art
In order to reduce the size of the microwave and millimeter wave circuit apparatus and perform mass production thereof, it is effective to prepare transmitter and receiver circuits of the microwave and millimeter wave as a multi-chip module (MCM) and make this transmitter and receiver circuits, which is the multi-chip module, as an integration block with an antenna. FIG. 7 schematically shows a microwave and millimeter wave circuit apparatus conventionally suggested as an integration module having an antenna.
In this conventional microwave and millimeter wave circuit apparatus, a metal case package 71 contains a monolithic microwave integrated circuit (MMIC) 72 and an antenna substrate 73 which are connected to each other by a bonding wire 74. Moreover, an intermediate frequency (IF) terminal 75 and a bias terminal 76 are connected to the MMIC 72 via a bonding wire 74. Moreover, an attempt has been made to prepare a microwave and millimeter wave circuit apparatus using a GaAs substrate. FIG. 8 schematically shows a conventional microwave and millimeter wave circuit apparatus using a GaAs substrate.
An MMIC substrate 81 has a receiver integrated circuit 81a formed on the GaAs substrate. Moreover, in an antenna substrate 82, a patch antenna 85 is provided on a quartz substrate. On the surface of the antenna substrate 82, a grounding metal cover 83 and a coupling slot 84 are formed. The MMIC substrate 81 and the antenna substrate 82 are bonded to each other, so that the circuit in the MMIC substrate 81 and the antenna 85 are connected to each other via the coupling slot 84.
However, in the conventional microwave and millimeter wave circuit apparatus shown in FIG. 7, the MMIC 72 and the antenna substrate 73 are only connected to each other only the wire bonding 74 and are contained in the package 71 in an airtight way. Accordingly, there is a limit to reduction in size and mass production. Especially in the millimeter wave circuit, there is a problem that because of parasitic elements such as inductance caused by the wire bonding 74, it is difficult to perform connections with a low loss and to assure performance repeatability. Furthermore, the patch antenna is connected to the RF circuit such as the MMIC on a plane-to-plane basis and a long feed line to the patch antenna is required. It is necessary to reduce the loss in the feed line. Moreover, in the conventional microwave and millimeter wave circuit apparatus shown in FIG. 8, there is a problem that it is necessary to accurately position the MMIC substrate 81 and the antenna substrate 82, complicating the assembling process. Furthermore, since circuit elements are provided on the upper and the lower surface of the apparatus, there is a problem that when mounted on a stage it is impossible to measure microwave and millimeter wave characteristics using a probe apparatus or the like.